Device and method for adjusting the shell of a ski boot to a foot

ABSTRACT

The invention relates to a device and to a method for producing a shell ( 2 ) of a ski boot ( 1 ) that in some areas is adapted to a foot, or a leg, of a user, comprising a lower and/or upper shell part ( 3, 3 ′) made of a plastic material, and a heating element ( 10 ) for sectionally heating the lower and/or upper shell part ( 3, 3 ′) above the softening temperature of the plastic material. The heating element ( 10 ) has an outer adhesion-promoting layer ( 11 ) for connecting the heating element ( 10 ) to one of the shell parts ( 3, 3 ′) of the ski boot ( 1 ).

The invention relates to a device for producing a shell of a ski boot that in some areas is adapted to a foot, or leg, of a user, comprising a lower and/or upper shell part made of a plastic material, wherein a heating element for sectionally heating the lower and/or upper shell part above the softening temperature of the plastic material is provided. Furthermore, the invention relates to a method for producing a shell of a ski boot that is adapted to a foot, or leg, of a user and comprises a prefabricated lower shell part—which has a substantially plate-shaped sole area—and/or an upper shell part made of a plastic material, wherein one of the shell parts is heated at least sectionally, wherein the foot of the user is accommodated in the heated state in the lower and/or upper shell part.

From WO 2014/015354 A1 there is already known a method and a device for the partial heating of a shell part of a ski boot. Here, a heating mat is used which is wrapped around the ski boot. The two ends of the heating mat will be connected with each other by means of a hook-and-loop fastener or the like, so that the heating mat contacts the shell part at least sectionally in order to obtain an efficient introduction of heat. Principally, said device works in a satisfactory manner, but the introduction of heat can only be determined relatively inaccurately, so that usually a larger region of the shell part is heated than would be necessary for an individual adaptation or adjustment in a neuralgic or sensitive area. The consequence thereof can be that the ski boot or the shell part at least partially changes its basic geometry in an undesired manner, which has an adverse effect on the force transmitted via the boot onto a ski. Furthermore, due to the slack lying-on of the heating mat only a relatively small efficiency with regard to the heat transfer can be achieved.

From WO 2011/153567 A1 there is further known an adaptation method comprising a bag-like pressure-exerting element. When adapting an alpine ski boot, the method and/or the known apparatus requires, however, an exact positioning of the base plate during the carrying-out of the adaptation method so that no unwanted deformation of the substantially plate-shaped sole area will be caused during the adaptation of the shell of the ski boot to the individual foot or leg of the user.

Furthermore, on the other hand, from EP 1 872 678 A2 there is known a ski boot which consists mainly of a relatively rigid plastic material. In those areas in which painful pressure sores will frequently occur, the ski boot comprises a material having a lower softening temperature so that the ski boot, when heated up to a special softening temperature, will only be deformable in the region of said sensitive areas. Such a production of a ski boot which in sections consists of different plastics or plastic compounds is, however, quite expensive and costly.

In ski boots, a deformation of the sole area is particularly disadvantageous as the form of the sole area contributes essentially to the security and stability of the connection between ski and ski boot. In contrast thereto, in an ice skate according to WO 02/28215 A1 the entire ice skate inclusive of the sole is heated, is enveloped completely and is pressurized from the outside and, thus, is potentially deformed.

On the other hand, the heating of an inner boot which consists substantially of textile fabrics is already known. In this connection, EP 824 874 A2 teaches to permanently integrate a heatable film in an inner boot. In DE 10 2007 002 335 A1 there is disclosed the permanent application of a heating element at the outside of an inner boot.

Hence, the aim of the present invention is to provide a device or a method by means of which a precise heating of a certain area of the shell part is enabled. Preferably, furthermore an improved efficiency of the heat transfer shall be achieved.

According to the invention this aim is achieved by means of a device of the kind mentioned at the beginning, in which the heating element comprises an outer adhesion-promoting layer for connecting the heating element to a shell part of the ski boot. By the provision of a heating element with an adhesion-promoting layer, the heating element can be attached at any positions of a shell part in a simple manner by means of an adhesion connection. By the contact between the heating element and the shell part established by means of the adhesion connection there will further be obtained—in contrast to a slack lying-on—an improved heat transfer from the heating element into the plastic material of the shell part. By means of the device according to the invention a precise and efficient partial heating of the shell part in a certain area of the shell part is achieved. In this connection, the heating element can be attached in particular in so-called neuralgic or sensitive areas at the shell part at which areas painful pressure sores frequently occur when the ski boot is used. These sensitive areas are in particular the outside of the ankle, the balls of the little toes, the base bumps, and, on the inner side of the ski boot, the inside of the ankle, the balls of the big toes and the navicular bone (os naviculare).

In order to be able to establish an adhering connection between the heating element and a shell part in a simple and efficient manner, it is favourable if a layer of an adhesive is provided as an adhesion-promoting layer.

When the layer of the adhesive comprises a reglueable pressure-sensitive adhesive, advantageously the device according to the invention can be reused; this means that, by means of the pressure-sensitive adhesive, the heating element can first of all be attached reliably in a neuralgic or sensitive area to be adapted to the foot of the user and can then be removed again from the shell part after the carried-out adaptation in said area, and then it can be positioned in a further region or area to be adapted, etc.

In order to avoid an excess softening through the heat emitted by the heating element and, thus, in order to guarantee that during the heat transfer a contact between the heating element and the shell part is given, it is advantageous if the layer of the adhesive comprises a reglueable pressure-sensitive adhesive. Tests have shown that satisfactory results are achieved in particular with the acrylate adhesive “A20” as sold by the company 3M Deutschland GmbH or with the adhesive tapes sold by the company Lohmann GmbH & Co KG under the brand “Duplocoll®”. Furthermore, also (electro) pads from the company Axelgaard Manufacturing Co. Ltd can be obtained, which have an acrylate-based adhesive layer which is suitable for being used as an adhesion layer for the device according to the invention.

As an alternative to a layer of an adhesive, as an adhesion-promoting layer there can also be provided a silicone layer, preferably made of an addition cross-linked two-component silicone rubber which is vulcanizable at room temperature. Also such a silicone layer can be used many times—just as is the case with an adhesion layer consisting of a reglueable pressure-sensitive adhesive. Accordingly, via the adhesion-promoting layer only a temporary adhesion connection between the shell part to be adapted and the heating element is established, and the heating element will be removed again from the shell part after the carried-out heating and adaptation of the shell part. As a further alternative to an adhesion-promoting layer comprising an adhesive it is also possible that an adhesion-promoting layer based on van der Waals forces is provided. Here, the adhesion area has a plurality of superfine hairs, wherein each hair can transfer a small force due to the electrostatic interaction, and by the high number of hairs the sum of the forces is sufficient to attach—as in the present case—the heating element at the shell part for the purpose of the heat transfer due to the electrostatic interaction. Such mats which are based on the so-called “gecko effect” are commonly known and are available on the market from different suppliers, inter alia as anti-slip mats for vehicles and so on.

In order to keep the weight and the material thickness of the heating element as small as possible so that the heating element can be held at the shell part already with relatively small forces, it is advantageous if the heating element comprises a heating film, preferably with a film thickness of less than 3 mm.

As a heating film or as a film-type heating element there can also be employed so-called silicone heaters. Accordingly, when the heating element comprises a silicone heater in which a heating conductor layer is accommodated between two silicone layers provided preferably with (glass) fabric inlays, advantageously a separate adhesion-promoting layer in addition to said layer in which the heating element is embedded can be omitted, and the silicone layer including the heating conductor layer can simultaneously form the adhesion-promoting layer due the high surface tackiness of the silicone material. It is of particular advantage to use a silicone heater on the basis of a silicone gel, i.e. that a silicone layer in which the heating conductor layer is accommodated is provided or that the heating conductor layer is embedded between two interconnected silicone layers on the basis of the silicone gel. Advantageously, silicone gels have a high surface tackiness and, consequently, an additional adhesion-promoting layer for the fixation at the upper surface of the boot is not required. In this connection, as a silicone gel there can be used in particular an addition cross-linked two-component silicone rubber which is vulcanizable at room temperature, wherein the two components A, B of the two-component silicone rubber may consist of polydemthylsiloxane with functional groups and auxiliaries, respectively. In this connection, component A can comprise in particular the cross-linking agent, whereas component B can comprise a catalyst, in particular a platinum catalyst. Such a two-component silicone rubber is for instance known from the company Wacker Chemie under the name of “Wacker SilGel® 612 A/B”, wherein in this case, however, a mixing ratio of 1:1 of the components A:B is provided in which the degree of cross-linking is too low for the use as a component of the silicone heater. That means, in case of a mixing ratio of 1:1 of the components A and B the gel is too tacky and too soft so that the manipulation of the application and then the removal on the upper surface of the boot is not possible without damaging the silicone heater. Practical tests have shown that with a mixing ratio of 1.4 to 1.6:1 of the components A:B, in particular of 1.45 to 1.5:1 of the components A:B, an elasticity or hardness of the vulcanizate can be obtained in which a sufficient tackiness is maintained, but that thereby the manipulation capability will be improved in such a way that a permanent usage is guaranteed.

Advantageously, in the heating film or in the silicone heater an etched conducting track, a strand or a wire, preferably made of an alloy containing copper and nickel, is integrated (or accommodated) as a heating conductor layer. In this connection it is favourable if the free spaces between the tracks of the heating conductor layer are formed such that the heating film or the silicone heater are deformable in all three dimension and, thus, that they can be adapted optimally to the three-dimensionally formed surface of the shell part.

Furthermore, it is favourable for the protection of the heating conductor layer, and without significantly deteriorating the efficiency of the heat transfer, if the heating conductor layer is accommodated between two insulating films preferably made of polyimide (so-called Kapton® heating films or foils) or polyester. Such heating films or the silicone heater with a heating conductor layer accommodated between two insulating films are also available on the market and are produced for instance by the company Winkler GmbH, Heidelberg, Germany.

In order to restrict the heat dissipation in the direction facing away from the shell part it is advantageous if a textile fabric and/or an insulating layer are provided on the side of the heating film or of the silicone heater which is facing away from the adhesion-promoting layer.

In order to be able to carry out an adjustment to a desired, preset temperature it is advantageous if the heating element comprises a temperature sensor or probe.

Furthermore it is favourable if the adhesion-promoting layer extends essentially completely over a contact surface of the heating element. In this case it is guaranteed that due to the substantially continuous adhesion-promoting layer the contact extends substantially over the entire contact surface so that a particularly efficient heat transfer can be achieved. In case of a silicone heater in which the material surrounding the heating conductor layer simultaneously forms the adhesion layer, the complete formation as an adhesion-promoting layer results advantageously already from the design.

The method according to the kind mentioned at the beginning is characterized according to the invention in that in a region of the lower shell part deviating from the sole area a heating element will be attached by means of an adhesion connection before the lower shell part will be heated in some areas by means of the heating element.

Hence, as already explained in connection with the device, it can be achieved in particular that the shell part will be partially heated in a precise and efficient manner in order to heat the shell part—locally—in sensitive areas above the softening temperature and consequently to adapt the shell part in some areas to the foot of the user—without (extensively) changing the basic geometry of the shell. Accordingly, painful pressure sores resulting from the use of the ski boot can be avoided without any losses in the force transmission.

With regard to an easy handling in which it is not necessary to manipulate the at least sectionally heated shell part it is advantageous if the foot or leg of the user is inserted into the lower shell part before the lower shell part will be heated.

In order to, on the one hand, reach the softening temperature of the preferably hard thermoplastic synthetic material—of which the lower and/or upper shell part usually consists—in the heated area without, however, causing a heat development within the ski boot—which would be disagreeable for the user—it is favourable if the lower shell part is heated up to at least 50° C., preferably up to a temperature between 50° C. and 100° C., in particular between 60° C. and 90° C.

In the following, the invention will be explained in further details by means of preferred embodiments represented in the drawings, without the invention being restricted thereto. In the drawings:

FIG. 1 shows a lateral side view of a ski boot known per se, with a lower shell part and a hinged collar;

FIG. 2 shows a medial side view of the ski boot according to FIG. 1;

FIG. 3 shows a view of the ski boot with an adhering heating element (partially shown);

FIG. 4 shows a view of a design of a heating conductor layer of a heating film;

FIG. 5 shows a view of an alternative design of a heating conductor layer of a heating film;

FIG. 6 shows a schematic sectional view through a heating element according to the invention; and

FIG. 7 shows a schematic sectional view through an alternative heating element according to the invention.

FIGS. 1 and 2 each shown a ski boot 1 known per se, with a lower shell or bootleg part 3 consisting of a hard thermoplastic synthetic material, at which shell or bootleg part 3 there is hinged an upper, collar-shaped shell part 3′. In the shell parts 3, 3′ there is accommodated a comparatively flexible inner shoe 5 which at least sectionally comprises a padding. The lower shell part 3 as well as the upper collar-shaped shell part 3′ each have closing elements 4, in particular buckles, in order to enable an easy getting-in of the foot or leg of the user or a sufficient support of the foot or leg of the user in the accommodated position.

Here, the lower shell part 3 has a plate-shaped sole area 5 for the purpose of connecting the ski boot 1 to a release or safety binding. In FIG. 1 and FIG. 2 there are represented by broken lines those neuralgic or sensitive areas in which painful pressure sores can frequently occur when using the ski boot 1. These sensitive areas are the outside 6 of the ankle, the balls 7 of the little toes, the base bumps 8 and, on the inner side of the ski boot 1, the inside 6′ of the ankle, the balls 7′ of the big toes and the navicular bone (os naviculare) 8′. In all said sensitive areas in particular a heating element 10 (see FIG. 3) can be attached by means of an adhesion layer 11.

In FIG. 3 the heating element 10 is shown in its position substantially adhering in the region of the base bump 8. Hereby it becomes obvious that by means of the represented heating conductor layer 12 (by omission of the layers arranged thereabove, see FIG. 6) the shell part 3 can be heated above the softening temperature of the plastic material precisely and only in a predetermined region by means of a heat transfer, and, consequently, in said region—and exclusively in said region—in which the heating element 10 is provided an adaptation to the foot of the user is carried out.

As becomes obvious from the sectional view according to FIG. 6, the heating conductor layer 12 which usually only has a thickness of less than 2 mm is accommodated between two insulating films 13 in a liquid-tight manner and, thus, forms a heating film 14 which is insulated in itself and is known per se and which is for instance offered for sale by the company Winkler GmbH, Heidelberg, Germany.

Above the heating film 14, in the embodiment as shown in FIG. 6 there is arranged a covering layer 15 made of a textile fabric which, advantageously, is provided with a thermocolor so that the color of the textile fabric changes in dependence on the temperature, and, thus, the current temperature of the heating element 10 can be identified in an easy manner for the user. Above, also an insulating layer 16 which, preferably, is transparent is provided in order to minimize the heat emission away from the shell part 3 and in order to prevent burn injuries of the skin in case of a contact, for instance with the hand of the user.

As is shown in the sectional view according to FIG. 7, as a heating element 10 there can in particular also be provided a silicone heater 14′ in which the heating conductor layer 12 is accommodated between two silicone layers 13′. Here, the silicone heater 14′ consists of the heating conductor layer 12 which is embedded in a manner protected against humidity between two thermally and mechanically stable silicone layers 13′ which are reinforced at best with a (glass) fabric inlay 20, respectively. The entire silicone heater element 14′ has been vulcanized to form a homogeneous unit, wherein no separate adhesion-promoting layer 11 has to be provided, but the silicone layer 13′ simultaneously forms the adhesion-promoting layer 11. A good compromise between the hardness of the silicone layer 13′ and the surface tackiness is obtained when for the production of the silicone layer(s) 13′ an addition cross-linked two-component silicone rubber is used, wherein the two components A, B preferably consist of polydemthylsiloxane with functional groups and auxiliaries, respectively. In this connection, component A comprises the cross-linking agent, whereas component B comprises a catalyst, in particular a platinum catalyst. Such a two-component silicone rubber is for instance known from the company Wacker Chemie under the name of “Wacker SilGel® 612 A/B”, wherein practical tests have shown that with a mixing ratio of 1.4 to 1.6:1 of the components A:B, in particular of 1.45 to 1.5:1 of the components A:B, an elasticity or hardness of the vulcanizate can be obtained in which a sufficient tackiness is maintained, but that thereby the manipulation capability will be improved in such a way that a permanent usage is guaranteed. It is a matter of course that the silicone heater 14′—like the heating element 10 according to FIG. 6—can be provided with a covering layer 15 and/or an insulating layer 16 on the side facing away from the adhesion-promoting layer 11.

In FIG. 3 there is further shown that the heating conductor layer 10 comprises electrical connection points 17 for connecting electrically conductive cables for the purpose of a connection with an external energy source, wherein in the shown embodiment two separate heating conductor tracks 18 each comprise their own connection point 17 with two contact points, respectively.

Thus, the heating element 10 lies substantially completely on the shell part 3 with a lower contact surface 19 so that a heat transfer from the heating element 10 onto the shell part 3 can be carried out in an efficient and precise manner. In this connection, advantageously the entire contact surface 19 is provided with the adhesion-promoting layer 11 so that a large-area contact between the heating element 10 and the shell part 3 is guaranteed by means of the adhesion connection.

In FIG. 4 and FIG. 5 there are shown even two further preferred embodiments of a heating conductor layer 12. Here it becomes in particular obvious that both conducting tracks 18 are designed such that the heating conductor layer 12 is deformable in a three-dimensional manner, respectively, and that thereby it can be adapted optimally to the three-dimensional form of the shell part 3.

In order to be able to individually, i.e. separately, adapt the above-mentioned neuralgic or sensitive areas by means of a heating element 10 in which there is provided a heating conductor layer 12—as is shown in FIG. 4 and FIG. 5—to the foot of the user, the heating conductor layer 12 shown in FIG. 4 has a diameter between 70 mm and 90 mm, in particular substantially 75 mm; the heating conductor layer 12 has a longitudinal extension between 80 mm and 120 mm, in particular substantially 100 mm, and a width between 40 mm and 80 mm, in particular substantially 60 mm.

In order to minimize the manipulation expenditure during the adaptation or adjustment, when carrying out the method according to the invention the foot or leg of the user is preferably arranged in the ski boot 1 already before the plastic material of the shell part 3 is heated above its softening temperature by means of a heating element 10 only in the desired region and without changing the basic form of the shell part 3. Hence, the heating element 10 will only be connected to the shell part 3 via the adhesion-promoting layer 11 temporarily for the heating of the shell part 3 above its softening temperature and will be removed again from the shell part after a successful adaptation and heating. 

1. A device for producing a shell of a ski boot that in some areas is adapted to a foot, or a leg, of a user, comprising a lower and/or upper shell part made of a plastic material, wherein a heating element for sectionally heating the lower and/or upper shell part above the softening temperature of the plastic material is provided, characterized in that the heating element comprises an outer adhesion-promoting layer for an adhesion connection of the heating element to one of the shell parts of the ski boot, wherein as an adhesion-promoting layer there are provided a layer of an adhesive comprising a reglueable pressure-sensitive adhesive, or a silicone layer, or an adhesion-promoting layer based on van der Waals forces.
 2. The device according to claim 1, wherein as a reglueable pressure-sensitive adhesive an acrylate-based pressure-sensitive adhesive is provided.
 3. The device according to claim 1, wherein the silicone layer consists of an addition cross-linked two-component silicone rubber which is vulcanizable at room temperature.
 4. The device according to claim 1, wherein the heating element comprises a heating film, preferably with a film thickness of less than 3 mm.
 5. The device according to claim 1, wherein the heating element comprises a silicone heater in which a heating conductor layer is accommodated between two silicone layers preferably provided with (glass) fabric inlays.
 6. The device according to claim 4, wherein in the heating film or in the silicone heater there is accommodated an etched conducting track, a strand or a wire, preferably made of an alloy containing copper and nickel, as a heating conductor layer.
 7. The device according to claim 6, wherein the heating conductor layer is accommodated between two insulating films preferably made of polyimide.
 8. The device according to claim 4, wherein on the side of the heating film or of the silicone heater which side faces away from the adhesion-promoting layer there are provided a covering layer, preferably a textile fabric, and/or an insulating layer.
 9. The device according to claim 1, wherein the heating element comprises a temperature sensor.
 10. The device according to claim 1, wherein the adhesion-promoting layer substantially extends completely over a contact surface of the heating element.
 11. A method for producing a shell of a ski boot that is adapted to a foot, or leg, of a user and comprises a prefabricated lower shell part—which comprises a substantially plate-shaped sole area—and/or an upper shell part made of a plastic material, wherein a shell part is heated at least sectionally, wherein the foot of the user is accommodated in the lower and/or upper shell part in the heated state, characterized in that in a region of one of the shell parts deviating from the sole area a heating element will be attached by means of an adhesion connection between the heating element and the shell part achieved via a reglueable pressure-sensitive adhesive, a silicone layer, or via van der Waals forces, before the shell part will be heated in some areas by means of the heating element.
 12. The method according to claim 11, wherein the foot or the leg of the user is inserted into the lower and/or upper shell part prior to heating the shell part.
 13. The method according to claim 11, wherein the lower and/or upper shell part is heated up to at least 50° C., preferably up to a temperature between 50° C. and 100° C., in particular between 60° C. and 90° C. 